Crank-driven reciprocating mechanisms

ABSTRACT

A crank driven reciprocating mechanism comprising a driven crank device, a connecting rod articulated to the eccentric crank of the crank device and carrying a shackle pin, and a shackle disposed transversely of the rod articulated to a fixable member on one side of the rod and on the other side of the rod to a reciprocable member and having between its ends a longitudinal slot engaged by the shackle pin. This mechanism can be used as the needle bar drive and if desired to drive the fabric feed mechanism of a stitching machine such as a tufting machine or a sewing machine.

United States Patent Ballamy Sept. 17, 1974 [54] CRANK-DRIVENRECIPROCATING 2,548,807 4 1951 Morgan et a1. 74 40 MECHANISMS 3,410,14511/1968 Hebcl 3,450,081 6/1969 Rabinow 112/212 [76] Inventor: LeslieMark Ballamy, Hallams Court, Blackheath, England Primary ExaminerSamue1Scott 22 Filed; Oct 7 Assistant Examiner-Wesley S. Ratliff, Jr.

Attorney, Agent, or Firm-Snyder, Brown and Ramik [21] App1. N0.: 190,889

[57] I ABSTRACT Foreign Application Priority Data A crank drivenreciprocating mechanism comprising a 0m. 23, 1970 Great Britain 50460/70driven crank device, a Connecting rod articulated t0 the eccentric crankof the crank device and carrying a 52 US. Cl. 74/40, 112/212 shackle pand a shackle disposed transversely of the 51 Int. c1. Fl6h 21/32 redarticulated to a fixeble member on one side of the [58] Field of Sear h1 12/221, 209, 210; 74/40 rod and on the other side of the rod to areciprocable 74/41 member and having between its ends a longitudinalslot engaged by the shackle pin. This mechanism can [56] Refere Cit d beused as the needle bar drive and if desired to drive UNITED STATESPATENTS the fabric feed mechanism of a stitching machine such 1,567,17212 1925 Powell 74 40 as a tuftmg machine or a Sewmg machme 2,082,3366/1937 Havener 74/40 16 Claims, 3 Drawing Figures PAIENIED SEP I 7 m4SHEET 3 0F 3 1 CRANK-DRIVEN RECIPROCATING MECHANISMS BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to crankdriven reciprocating mechanisms and inter alia is suitable. for drivingthe reciprocating needle and looper-cutting mechanism of a tuftingmachine and the feed mechanism for advancing the base cloth through thetufting station. The mechanism of the invention may however be used inany drive where it is desirable to impart a reciprocating movement of amember from a rotary drive member.

The main object of the present invention is to provide a crank drivenreciprocating mechanism drive which may permit variation of the strokeof the member reciprocated by the drive and/or stopping and, startingthe movement of the reciprocating member independently of its rotarydrive element and/or permitting variations in an oscillating motionimparted to a member from a rotary drive element. The invention will bedescribed by way of example with reference to a tufting machine 2.Description of the Prior Art Known tufting machines suitable foroperation in the home or by operatives in a factory have a frame formedwith a flat elongated base having at one end a base cloth feedingmechanism and a looping and cut off device, an upright at the other endof the base and a needle mechanism supported over the feeding andlooping and cut off mechanisms in a cantilever arm extending from theupper end of the upright in the form generally associated withconventional. domestic sewing machines. The said mechanisms are drivenby a driving mechanism which may be hand operated or driven by a primemover such as an electric motor as in sewing machines. The driven shaftthrough gears or belt drives incorporating speed reduction means drivestwo shafts, one in the base driving the feed and looping and cut offmechanisms and the other in the cantilever arm driving the needlemechanism, all the mechanisms being driven in timed relation and atspeeds ensuring the needle, feed, looper and cutter all operating inaccurate timed relation. Such tufting machines have a reciprocatingneedle bar driven from the rotary shaft in the centilever arm andreciprocating through a throat plate in the base of the frame to carryyarn downwardly through an aperture therein. The looper, and cutter aremounted below the throat plate and the base fabric to receive a tuftedpile is fedover the throat plate by the feeder which holds the fabricstationary during the needle movement therethrough, moving fabric onintermittently during movements of the reciprocating needle above thefabric. The looper cooperates with the needle to collect the loops ofyarn passed by the needle through the fabric and throat plate and thecutter cooperates with the looper to cut the yarn threads looped overthe looper to form tufts on the fabric.

SUMMARY According to the present invention a crank driven reciprocatingmechanism comprises a driven crank device, a connecting rod articulatedto the eccentric crank of the crank device and carrying a shackle pin,

and a shackle disposed transversely of the rod articulated to a fixablemember on one side of the rod and on the other side of the rod to areciprocatable member and having between its ends a longitudinal slotengaged by the shackle pin.

In one construction means are provided to vary the position of thefixable member and/or the articulated connection of the shackle to thereciprocable member to vary the stroke of the reciprocable memberwithout stopping rotation of the crank device.

A lever may be pivoted with respect to the fixable member and has a linkarticulated thereto carrying a link pin engaging in a longitudinal slotin the connecting rod for relative movement betweenrod and link pin suchthat by pivoting the lever the position of the link pin in the slot maybe varied to vary the amplitude of oscillation of the reciprocablemember.

The fixable member is preferably mounted on the rod connected to apiston in a fluid controlled cylinder and- /or the reciprocable memberis connected to a piston in a fluid controlled cylinder and a fluidcontrol valve is provided to move the piston or one of the pistons toenable the reciprocable member to be stopped or started instantaneouslywithout stopping rotation of the crank device.

The connecting rod may be provided with a slot and a pivoted arm ismounted on an oscillated member and having a slot at an angle to theslot in the connecting rod, and a pin rides in both slots wherebyrocking of the connecting rod by the crank device causes oscillation ofthe arm. I

From another aspect of the invention a needle bar drive mechanism isprovided, the needle bar forming the reciprocable member of theinvention and the crank drive mechanism of the invention is the drivefor the needlebar.

The oscillatable arm of one preferred crank driven mechanism of theinvention may be fixed to a feed mechanism assembly of the tuftingmachine.

The invention also provides a tufting machine having a reciprocatingneedlebar and an oscillatable feed mechanism driven by the preferredcrank drive mechanism of the invention, or a sewing machine driven bysuch mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may bemore fully understood an embodiment in accordance therewith will now bedescribedby way of example with reference to a tufting machine, thedescription being of a tufting machine shown in the accompanyingdrawings, in which:

FIG. 1 is a longitudinal cross section through a tufting machine;

FIG. 2 is an end elevation of the machine of FIG. 1 with the end coversremoved looking from the left in FIG. 1, and

FIG. 3 is a perspective view on an enlarged scale of the tuftingmechanism in the machine of FIGS. 1 and 2.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawings, the same referencesare used to designate the same parts.

Referring to the drawings, the machine frame comprises a base 1, alooper and cutter assembly (FIG. 3) mounted at one end of the base, anupright 2 at the other end of the base supporting a cantilever arm 3which extends over and substantially parallel to the base and supports aneedle mechanism at its outer endv over the looper and cutter assemblyin the general manner of a domestic sewing machine. The looper andcutter assembly is driven by a shaft 4 journalled in the base and theneedle mechanism is driven by a shaft 5 journalled in the cantileverarm, the two shafts 4, 5 being driven by an electric motor mounted onthe frame (not shown) through a belt drive 7 through appropriate timedpulleys and/or gears. The looper and cutter assembly is supported by abody 8 and will now be described to assist in understanding theinvention but it forms no part of the present invention.

A bore 9 extends through the body about a transverse axis offsetforwardly from'the centre of the body and is lined to provide a bearingfor the drive shaft 4. The body is extended downwardly at one endthereof (hereinafter referred to as the outer end) in a projection 11terminating in a pair of longitudinally spaced arcuate jaws defining atransversely extending threaded cylindrical bore 12. These jaws arejoined at their lower ends by a bolt 15 extending longitudinally througha plain bore in the forward jaw to be threadably received in a threadedbore in the rearward jaw. The body also is extended rearwardly at itsouter end in a second projection 14 through which a plain bore extendsabout a transverse axis. An axle 16 extends from the outer end of boreto constitute a pivotal mounting for a cutter assembly. This cutterassembly comprises a tubular sleeve 17 having a planar cutter shaft 18extending radially from the outer end thereof and an operating arm 19extending radially from the other (i.e., inner) end I thereof. Theoperating arm 19 is angularly spaced from the cutter shaft.

The cutter shaft is formed at its radially outer end in a rectangularblock 20 which has its elongate axis coplanar with but inclined slightlyfrom that of the shaft 18 and carries at its upper end a hardenedcutting edge 21. A parallel-sided slot 22 extends through the block 20in the direction of the elongate axis of that block for a purposehereinafter described.

The operating arm 19 is formed at its radially outer end with a yokeconstituted by a pair of arms spaced parallel in a radial plane of thesleeve 17. The tubular sleeve is a sliding and rotatable fit about theaxle l6 and is located thereon with the operating arm 19 adjacent thebody.

The drive shaft 4 has at its outer end a rotary eccentric 23 having ablock 24 pivotally mounted on an offset pivot pin extending axiallytherefrom. This block is a sliding fit in the yoke of the operating armand is retained therein by abutment of a pair of flanges formed at theouter end of the block with the outer faces of the yoke arms.

A looper axle 25 formed at one end with a threaded portion of increaseddiameter is threadably received from that end in the bore 12 and isclamped therein by the bolt 9 drawing the arcuate arms of projection 11together. A looper assembly is carried on the axle 25 and comprises atubular sleeve 28 having a planar looper shaft 29 extending radiallyfrom the centre thereof. The shaft 29 carries a looper head 30 formed ofa planar substantially triangular base portion having an end of one edgethereof extended outwardly in an arcuate looper hook 31, the free end ofwhich extends forwardly in spaced parallel relationship to the remainderof the said edge. The head 30 is attached to the shaft 29, in a radialplane of the sleeve 28 by a screw 32 passing through a hole in the apexof the base portion remote from the looper hook and threadably receivedin a cooperating threaded bore in the shaft 29. The looper head ismaintained by screw 32 with the looper hook radially outermost andextending substantially perpendicularly to the radial direction. A slot33 extends through a base portion of the looper head immediately belowthe base of the looper hook to provide access to a threaded bore in theradially outer end of the looper shaft. This slot 33 enables limitedarcuate adjustment of the position of the looper head on the loopershaft whilst still providing for access to the threaded bore. Thetubular sleeve is slidably received about the intermediate portion oflooper axle 25 with the looper head outermost and is spaced from theinner shoulder thereof by a spacer 34. A second spacer 35 abuts theouter end of the sleeve and a compression spring 36 is disposed aboutthe axle 25 to act between spacer 35 and a nut 37 threadably received onthe threaded outer end of the axle 25.

A pin 38 formed at one end with an externally threaded portion ofreduced diameter and at the other end with a slotted head of increaseddiameter extends through the slot 22 in the cutter assembly and throughthe slot 33 in the looper assembly and is threadably received in theradially outer bore of the looper shaft 29 so that the shoulder of thepin abuts the outer surface of the looper head 30. A block 39 flanged atits outer end to prevent passage through the slot and having a boreextending transversely therethrough is a sliding fit about the pin 38and is urged into the slot 22, with its flanged end in abutment with theouter face of the block 20 by a compression spring 40 acting between theflanged outer end of the block and the head of the pin 38.

In operation, rotation of the drive shaft 4 is transmitted to thepivotally mounted block 24 which moves in the yoke of the operationalarm 19 to impart oscillatory motion to that arm. This motion istransmitted to the cutter shaft 18 formed integrally with theoperational arm causing the cutting edge to oscillate. Oscillation ofthe cutter shaft also causes the block 39 mounted in slot 22 to impartcorresponding oscillatory motion to the looper assembly. Spring 36 onlyserves to hold the looper assembly against spacer 34 and adjustment ofthe extent to which looper shaft 25 extends into threaded bore 12enables the looper to be adjusted relative to the needle of the tuftingmachine in which the assembly is to be incorporated.

The adjustment of the looper shaft does not affect the pressure ofwiping engagement which is predetermined by the strength of spring 40.

The feed mechanism comprises a cam and roller freewheel assembly in acylindrical casing 41 the inner end of the casing 41 being keyed to adriven shaft 42 fast on the needle bar casing 43. The outer element ofthe freewheel assembly has a pair of pulleys 44 rotatable therewith oneither side of the casing 41 and the cam and roller assembly is suchthat the pulleys can only be driven in a clockwise direction in FIG. 2.The shaft 42 is driven from the shaft 5.

The shaft 5 has a rotary crank member 45 (which may be an eccentric)keyed thereto the crankpin 46 of which is articulated to a connectingrod 48 whose lower end is connected to a slotted element having a slot49. This rod-slotted element has a pin 50 fixed to it and this rides ina slot 51 in a shackle 52 pivoted at one end to the needle bar 53 and atits other on a pin 54 on a rod 55, to be described.

A lever 56 is pivoted on the shaft 42 and has a slot 57 in which the pin70 moves, the lever 56 being out of alignment with the rod 48. The feeddrive mechanism has an arm 58 urged upwardly by a spring 59 connected tothe arm and a projection 60 on the casing 43. A rod 61 is disposedbetween the arm 58 and a nose 62 on a hand operated lever 63 pivoted at64 to the casing 43. By moving the lever 63 upwardly the feed mechanismis pivoted about the shaft 42 to raise the feed rollers off a throatplate 65 above the looper-cutter assembly.

Rotation of the crank member 45 oscillates the pivots of the shackle 52about the pin 54 and thus reciprocates the needle bar 53 vertically inits guides in the casing 43, and the stroke of the needle bar can bevaried by raising or lowering a stitch control lever 66 pivoted at 67 tothe rod 55 and at 68 to a link 69 extending downwardly and carrying a.pin 70 riding in the two slots 49, 57.

For independent stopping and starting of the needle bar the link 67 istelescopic in length and so arranged that when the needle bar is held,for example at the top of its stroke, the pivotal connection 71 of theshackle to the needle bar becomes the fulcrum upon which the shacklehinges and the pin 50 will oscillate in its telescopic link. Bysimultaneously releasing the pin 50 and holding the needle, e.g. at thetop of its stroke, and vice versa, the needle bar may be stopped andstarted instantaneously without interfering with the rotation of theshaft 5. Any known means may be employed to effect the change over suchas mechanical interlock, fluid actuated rams or solenoids. Theconstruction of the slotted rod 48 and lever 56 with their slots engagedby the pin 70 causes them to cooperate in transmitting oscillatorymotion to the feed mechanism about the shaft 42. Movement of the pin 70along the slots 49, 57 in either direction varies the amplitude of thefeed mechanism oscillation.

One means of instantaneously stopping and starting the needle bar 53will now be described. The pivot 67 is carried on a rod 73 which extendsinto a cylinder 74 in the casing 43 and has a piston 75 mounted on it.The upper end of the needle bar enters another cylinder 76 and has apiston 77 mounted on it. Operating fluid under pressure is admitted toand escapes from the cylinder 74, 76 through ports 78, 79 respectivelyunder control of valves shown diagrammatically at 80.

In normal operation fluid under pressure is admitted to the cylinder 74through the port 78 on the underside of the piston 75 so that the pivot67 and the link 55 are held in the top position enabling the needle barto reciprocate in its guides in the normal manner. To interrupt theneedle bar the fluid in the cylinder is released by operation of thevalve 80 and fluid is admitted through port 79 to the underside of theneedle bar piston 77 which is then held at the top of its stroke whilethe rod 55 with its associated components oscillates freely. Thus themain drive is not affected by stopping and/or starting the needle bar.

I claim:

1. A crank driven reciprocating mechanism comprising a driven crankdevice, mounted in a frame, a connecting rod articulated to theeccentric crank of said crank device, a shackle pin carried by saidconnecting rod, a member fixable with respect to said frame, a

are provided to adjust the position of said fixable member to vary thestroke of said reciprocable member without stopping rotation of saidcrank device.

3. A mechanism according to claim 1 wherein means are provided to adjustthe position of said articulated connection of said shackle to saidreciprocable member to vary the stroke of the latter without stoppingrotation of said crank device.

4. A mechanism according to claim 1 wherein a lever is pivoted withrespect to said fixable member, a link is articulated to said lever, alongitudinal slot in said connecting rod, and a link pin carried by saidlink engaging in said connecting rod slot permitting relative movementbetween said rod and said link such that pivotal movement of said levervaries the position of said link pin in said connecting rod slot and theamplitude of oscillation of said reciprocable member.

5. A mechanism according to claim 1 wherein said fixable member ismounted on a rod connected to a piston in a fluid controlled cylinderand a fluid control valve is provided, said valve controlling pressurefluid flow to said cylinder to move said fixable member and permit saidreciprocable member to be stopped without stopping rotation of saidcrank device.

6. A mechanism according to claim I wherein said reciprocable member isconnected to a piston in a fluid controlled cylinder and a fluid controlvalve is provided, said valve controlling pressure fluid flow to saidcylinder to permit said reciprocable member to be stopped withoutstopping rotation of said crank device.

7. A mechanism according to claim 1 wherein a slot is provided in saidconnecting rod, an oscillable member is mounted in said frame, a pivotedarm is mounted on said oscillatable member and has a longitudinal slottherein, said arm slot being at an angle to said slot in said connectingrod, and a pin rides in both said slots whereby rocking of saidconnecting rod by said crank device causes oscillation of said arm.

8. A needle bar drive mechanism for a stitching machine comprising adriven crank device rotatably mounted in said machine frame, aconnecting rod articulated to the eccentric crank of said crank device,a shackle pin carried by said connecting rod, a member fixable withrespect to said frame, a shackle disposed transversely of saidconnecting rod and articulated to said fixable member on one side ofsaid rod, said shackle on the other side of said rod being articulatedto a needle bar reciprocable in said frame, and a longitudinal slot insaid shackle engaged by said shackle pin whereby rotation of said crankdevice imparts a reciprocatory motion to said needle bar.

9. A mechanism according to claim 8 wherein means are provided to adjustthe position of said fixable member to vary the stroke of said needlebar without stopping rotation of said crank device.

10. A mechanism according to claim 8 wherein means are provided toadjust the position of said articulated connection of said shackle tosaid needlebar to vary the stroke of the latter without stoppingrotation of said crank device.

11. A mechanism according to claim 8 wherein a lever is pivoted in saidframe with respect to said fixable member, a link is articulated to saidlever, a longitudinal slot is provided in said connecting rod, and avlink pin carried by said lever engages in said connecting rod slot andpermits relative movement between said rod and said link such thatpivotal movement of said lever varies the position of said link pin insaid connecting rod slot and the amplitude of oscillation of said needlebar.

12. A mechanism according to claim 8 wherein said fixable member ismounted on a rod connected to a piston in a fluid controlled cylindersupported by said frame and a fluid control valve is provided, saidvalve controlling pressure fluid flow to said cylinder to move saidfixable member and permit said needlebar to be stopped without stoppingrotation of said crank device.

13. A mechanism according to claim 8 wherein said needle bar isconnected to a piston in a fluid controlled cylinder supported by saidframe and a fluid control valve is provided said valve controllingpressure fluid flow to said cylinder to permit said needle bar to bestopped without stopping rotation of said crank device.

14. A mechanism according to claim 8 wherein a slot is provided in saidconnecting rod, an oscillatable fabric feed mechanism is mounted in saidframe to cooperate with a reciprocatable needle clamped to saidneedlebar, a pivoted arm is mounted on said feed mechanism and has alongitudinal slot therein, said arm slot being at an angle to said slotin said connecting rod, and a pin rides in both said slots wherebyrocking of said connecting rod by said crank device causes oscillationof said feed mechanism in timed relation to the reciprocable movement ofsaid needlebar.

15. A stitching machine comprising a frame having a base supporting astitching mechanism and a throat plate above said mechanism an uprightsupport on said base remote from said mechanism, a cantilever armmounted on said upright support spaced above and over said base, aneedle bar drive mounted in said cantilever arm with a reciprocableneedle bar in alignment with and passing a needle head thereon, in andout of the throat in said throat plate, a fabric feed mechanismsupported adjacent said needle bar and said throat plate above thelatter, and a crank drive mechanism driving said needle bar and feedmechanism, said crank drive mechanism comprising a driven crank devicerotatably mounted in said machine frame, a connecting rod articulated tothe eccentric crank of said crank device, a shackle pin carried by saidconnecting rod, a member fixable with respect to said frame, a shackledisposed transversely of said connecting rod and articulated to saidfixable member on one side of said rod, said shackle on the other sideof said rod being articulated to a needle-bar reciprocable in saidframe, and a longitudinal slot in said shackle engaged by said shacklepin whereby rotation of said crank device imparts a reciprocatory motionto said needle bar.

16. In a drive mechanism, in combination:

a rotatable drive shaft;

a first reciprocable member disposed to one side of the axis of saiddrive shaft;

a second reciprocable member disposed on the other side of said axis ofthe drive shaft;

a link member pivotally connected at its opposite ends respectively tosaid first reciprocable member and to said second reciprocable member;

a connecting rod on said drive shaft drivingly connected to said linkmember between said opposite ends thereof; and

means for selectively holding one of said reciprocable members fixedwhile allowing reciprocation of the other, and vice versa, whereby toselect either of said reciprocable members for movement withoutinterfering with rotation of said drive shaft.

1. A crank driven reciprocating mechanism comprising a driven crankdevice, mounted in a frame, a connecting rod articulated to theeccentric crank of said crank device, a shackle pin carried by saidconnecting rod, a member fixable with respect to said frame, a shackledisposed transversely of said connecting rod and articulated to saidfixable member on one side of said rod, said shackle on the other sideof said rod being articulated to a reciprocable member, a longitudinalslot in said shackle engaged by said shackle pin whereby rotation ofsaid crank device imparts a reciprocatory motion to said reciprocablemember and means for selectively fixing said reciprocable member whilereleasing said member fixable with respect to said frame and vice versa.2. A mechanism according to claim 1 wherein means are provided to adjustthe position of said fixable member to vary the stroke of saidreciprocable member without stopping rotation of said crank device.
 3. Amechanism according to claim 1 wherein means are provided to adjust theposition of said articulated connection of said shackle to saidreciprocable member to vary the stroke of the latter without stoppingrotation of said crank device.
 4. A mechanism according to claim 1wherein a lever is pivoted with respect to said fixable member, a linkis articulated to said lever, a longitudinal slot in said connectingrod, and a link pin carried by said link engaging in said connecting rodslot permitting relative movement between said rod and said link suchthat pivotal movement of said lever varies the position of said link pinin said connecting rod slot and the amplitude of oscillation of saidreciprocable member.
 5. A mechanism according to claim 1 wherein saidfixable member is mounted on a rod connected to a piston in a fluidcontrolled cylinder and a fluid control valve is provided, said valvecontrolling pressure fluid flow to said cylinder to move said fixablemember and permit said reciprocable member to be stopped withoutstopping rotation of said crank device.
 6. A mechanism according toclaim 1 wherein said reciprocable member is connected to a piston in afluid controlled cylinder and a fluid control valve is provided, saidvalve controlling pressure fluid flow to said cylinder to permit saidreciprocable member to be stopped without stopping rotation of saidcrank device.
 7. A mechanism according to claim 1 wherein a slot isprovided in said connecting rod, an oscillable member is mounted in saidframe, a pivoted arm is mounted on said oscilLatable member and has alongitudinal slot therein, said arm slot being at an angle to said slotin said connecting rod, and a pin rides in both said slots wherebyrocking of said connecting rod by said crank device causes oscillationof said arm.
 8. A needle bar drive mechanism for a stitching machinecomprising a driven crank device rotatably mounted in said machineframe, a connecting rod articulated to the eccentric crank of said crankdevice, a shackle pin carried by said connecting rod, a member fixablewith respect to said frame, a shackle disposed transversely of saidconnecting rod and articulated to said fixable member on one side ofsaid rod, said shackle on the other side of said rod being articulatedto a needle bar reciprocable in said frame, and a longitudinal slot insaid shackle engaged by said shackle pin whereby rotation of said crankdevice imparts a reciprocatory motion to said needle bar.
 9. A mechanismaccording to claim 8 wherein means are provided to adjust the positionof said fixable member to vary the stroke of said needle bar withoutstopping rotation of said crank device.
 10. A mechanism according toclaim 8 wherein means are provided to adjust the position of saidarticulated connection of said shackle to said needlebar to vary thestroke of the latter without stopping rotation of said crank device. 11.A mechanism according to claim 8 wherein a lever is pivoted in saidframe with respect to said fixable member, a link is articulated to saidlever, a longitudinal slot is provided in said connecting rod, and alink pin carried by said lever engages in said connecting rod slot andpermits relative movement between said rod and said link such thatpivotal movement of said lever varies the position of said link pin insaid connecting rod slot and the amplitude of oscillation of said needlebar.
 12. A mechanism according to claim 8 wherein said fixable member ismounted on a rod connected to a piston in a fluid controlled cylindersupported by said frame and a fluid control valve is provided, saidvalve controlling pressure fluid flow to said cylinder to move saidfixable member and permit said needlebar to be stopped without stoppingrotation of said crank device.
 13. A mechanism according to claim 8wherein said needle bar is connected to a piston in a fluid controlledcylinder supported by said frame and a fluid control valve is providedsaid valve controlling pressure fluid flow to said cylinder to permitsaid needle bar to be stopped without stopping rotation of said crankdevice.
 14. A mechanism according to claim 8 wherein a slot is providedin said connecting rod, an oscillatable fabric feed mechanism is mountedin said frame to cooperate with a reciprocatable needle clamped to saidneedlebar, a pivoted arm is mounted on said feed mechanism and has alongitudinal slot therein, said arm slot being at an angle to said slotin said connecting rod, and a pin rides in both said slots wherebyrocking of said connecting rod by said crank device causes oscillationof said feed mechanism in timed relation to the reciprocable movement ofsaid needlebar.
 15. A stitching machine comprising a frame having a basesupporting a stitching mechanism and a throat plate above said mechanisman upright support on said base remote from said mechanism, a cantileverarm mounted on said upright support spaced above and over said base, aneedle bar drive mounted in said cantilever arm with a reciprocableneedle bar in alignment with and passing a needle head thereon, in andout of the throat in said throat plate, a fabric feed mechanismsupported adjacent said needle bar and said throat plate above thelatter, and a crank drive mechanism driving said needle bar and feedmechanism, said crank drive mechanism comprising a driven crank devicerotatably mounted in said machine frame, a connecting rod articulated tothe eccentric crank of said crank device, a shackle pin carried by saidconnecting rod, a member fixable with respect to said frame, a shacklEdisposed transversely of said connecting rod and articulated to saidfixable member on one side of said rod, said shackle on the other sideof said rod being articulated to a needle-bar reciprocable in saidframe, and a longitudinal slot in said shackle engaged by said shacklepin whereby rotation of said crank device imparts a reciprocatory motionto said needle bar.
 16. In a drive mechanism, in combination: arotatable drive shaft; a first reciprocable member disposed to one sideof the axis of said drive shaft; a second reciprocable member disposedon the other side of said axis of the drive shaft; a link memberpivotally connected at its opposite ends respectively to said firstreciprocable member and to said second reciprocable member; a connectingrod on said drive shaft drivingly connected to said link member betweensaid opposite ends thereof; and means for selectively holding one ofsaid reciprocable members fixed while allowing reciprocation of theother, and vice versa, whereby to select either of said reciprocablemembers for movement without interfering with rotation of said driveshaft.